Blackberry-maker Research In Motion (RIM) has said its co-chief executives Mike Lazaridis and Jim Balsillie have stepped down in a shake-up.

Mr Lazaridis, who founded RIM in 1984, will become vice chairman. Mr Balsillie will continue to sit on the board but not have any operational role. Chief operating officer Thorsten Heins will replace them on Monday.

Investors have called for a strategy change as the company struggles to compete with Apple and Google. Mr Lazaridis, speaking after the announcement, said he recognized things needed to change at the company.

Mr Heins started at RIM in 2007, having previously worked at Siemens Communications. He became the chief operating officer in August 2011, according to the company. Barbara Stymiest, who has been on the board of RIM since 2007, has been made the new chairman, a post that Mr Balsillie and Mr Lazaridis also shared.

Blackberry, which was once extremely popular with users has suffered major setbacks in recent months. It had its worst service outage in 2011 and has been losing market share to its competitors in the smart phone markets. Billions of dollars have been wiped from its market value as shares have tumbled 75% over the past 11 months and sales have dropped.